Clarify

Co-authored-by: Sarah Rainsberger <[email protected]>

.changeset/green-suns-drive.md

@@ -50,4 +50,4 @@ Astro 5.0 introduces a new version of [content collections](https://docs.astro.b
 
 1. **Update other collections.** To update any other collections you may have, follow the [“Updating existing collections”](https://docs.astro.build/en/guides/upgrade-to/v5/#updating-existing-collections) section in the Astro 5 upgrade guide.
 
-If you are unable to make any changes to your collections at this time, you can enable the [`legacy.collections` flag](https://docs.astro.build/en/reference/legacy-flags/) which is supported by Starlight and will allow you to keep your collections in their current state until the legacy flag is no longer supported.
+If you are unable to make any changes to your collections at this time, including Starlight's default `docs` and `i18n` collections, you can enable the [`legacy.collections` flag](https://docs.astro.build/en/reference/legacy-flags/) to upgrade to v5 without updating your collections. This legacy flag exists to provide temporary backwards compatibility, and will allow you to keep your collections in their current state until the legacy flag is no longer supported.